The roofs of sports cars often have a limited longitudinal span, and do not afford an adequate space for conventional inner slide sunroof panels. Motor vehicles having a curved roof panel also do not afford an adequate space for an inner slide roof panel without substantially limiting the head clearance of the passenger compartment. To eliminate such problems, and to maximize the opening area of the sunroof for the given roof configuration, outer slide sunroofs are increasingly preferred for automotive sunroofs. In an outer slide sunroof, a rear end of the sunroof panel is lifted before the sunroof panel is slid rearward along the outer surface of the roof.
In an outer slide sunroof panel, a drain channel is required to be placed immediately below the rear edge of the sunroof opening to receive water drips from the fixed roof, as well as below the front and side edges of the sunroof opening. Conventionally, such a rear drain channel was secured, by using threaded bolts, to a roof inner frame which supports slide guide rails for the slide roof panel. In some cases, a rear drain channel was integrally formed in the roof inner frame by stamp forming.
However, there is a growing demand to simplify the sunroof structure, and reduce the overall thickness of the assembly to maximize the head clearance of the passenger compartment. To meet such a demand, it is desired to use extruded aluminum members having a side drain channel and a slide panel guide integrally formed therein. U.S. Pat. No. 5,718,472 issued Feb. 17, 1998 to J. Otake et al and assigned to the common assignee discloses an automotive sunroof of this type. The contents of this patent are hereby incorporated in this application by reference. The extruded aluminum members can be directly attached to the inner surface of the roof panel. However, attaching a rear drain channel member to the side drain channel members creates some problems. Aluminum members are not suited for self-tapping screws. It is therefore desired to attach the rear drain channel member to the roof panel jointly with the side drain channel members. However, the rear drain channel member must extend across the rear ends of the side drain channel members, and it is extremely difficult to allow the rear drain channel member and the side drain channel members to be jointly attached to the roof panel while allowing smooth flow of rainwater from the rear drain channel to the side drain channels.